An unbiased, quantitative and versatile method for determining misaligned and lagging chromosome during mitosis

Abstract

Accurate chromosome alignment at metaphase facilitates the equal segregation of sister chromatids to each of the nascent daughter cells. Lack of proper metaphase alignment is an indicator of defective chromosome congression and aberrant kinetochore-microtubule attachments which in turn promotes chromosome missegregation and aneuploidy, hallmarks of cancer. Therefore, tools to sensitively and quantitatively measure chromosome alignment at metaphase will facilitate understanding of how changes in the composition and regulation of the microtubule attachment machinery impinge on this process. In this work, we have developed and validated a method based on analytical geometry to measure several indicators of chromosome misalignment. We generated semi-automated and flexible ImageJ2/Fiji pipelines to quantify kinetochore misalignment at metaphase plates as well as lagging chromosomes at anaphase. These tools will ultimately allow sensitive, unbiased, and systematic quantitation of these chromosome segregation defects in cells undergoing mitosis.